<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        section {
            width: 400px;
            height: 50vh;
            display: flex;
            align-items: center;
            justify-content: center;
            font-size: 2rem;
        }
        .wrapper {
            width: 400px;
            height: 300px;
            overflow: auto;
            scroll-behavior: smooth;
        }
        #section1 {
            background-color: lightcoral;
        }
        #section2 {
            background-color: lightblue;
        }
        #section3 {
            background-color: lightgreen;
        }
    </style>
</head>
<body>
    <nav>
        <ul>
            <li><a href="#section1">部分 1</a></li>
            <li><a href="#section2">部分 2</a></li>
            <li><a href="#section3">部分 3</a></li>
        </ul>
    </nav>
    
    <div class="wrapper">
        <section id="section1">部分 1</section>
        <section id="section2">部分 2</section>
        <section id="section3">部分 3</section>
    </div>
</body>
</html>